Decreased Pulmonary Blood Flow

Some congenital heart defects send too little blood through the pulmonary circulation. The resulting cyanosis is cardiac: blood reaches the systemic circulation without adequate oxygenation because pulmonary outflow is obstructed or because the normal route through the right heart is absent. The bedside priority is to distinguish this pattern from primary lung disease, then identify whether the child is stable, experiencing a hypercyanotic spell, or dependent on a patent ductus arteriosus for pulmonary blood flow.